Strip material

ABSTRACT

The invention relates to a material in the form of a strip having a stiffening corrugation thereon. The corrugation consists of ridges and valleys therebetween which form arcs over the breadth of the corrugation zone. The corrugations form a wave pattern propagating in the longitudinal direction of the strip. The waves have no straight sections, and the relationship between the thickness of the strip T and the corrugation depth A is 0.5T&lt;A&lt;2T. In addition, the height of the arcs is at least as large as the wave length of the waves propagating in the Y-direction and alternating in the Z-direction.

TECHNICAL FIELD

The invention relates to a material in the form of a strip, plate, foil,sheet, board or corresponding, provided with a corrugation or embossingwhich increases the stiffness of the material but at the same time makesit possible to bend the material to a high degree without exceeding it'syield point, i.e. without causing permanent deformation, whichcorrugation or embossing has the shape of ridges and valleystherebetween, the isohypsis of said ridges and valleys, within theregion of a conceived strip shaped zone of the material, forming arcswhen projected on an X-Y-plane in a three dimensional coordinate system,in which the X-direction coincides with the longitudinal direction ofthe corrugated zone, the Y-direction coincides with the breadthdirection of the corrugated-zone, and the Z-direction is perpendicularto the X-Y-plane, while sections in the Y-Z-plane form a wave patternconsisting of waves alternating in the Z-direction.

BACKGROUND ART

Corrugation or embossing is a conventional means of increasing thestiffness and the resistance against bending of comparatively thinmaterials in at least one direction. The technique is used in a varietyof applications. For example may be mentioned corrugated sheet iron.Corrugated board is another example, as according to DE-A1-2 211 925.Also in nature there are many shapes where folding patterns and the likegive increased stiffness. It is in these examples often the question ofcomparatively thin materials, i.e. blades on flowers and grass, etc.

BRIEF DESCRIPTION OF THE INVENTION

It is an object of the invention to provide a new corrugation patternwhich can be applied on the kinds of material mentioned in the preamblein order to increase the resistance to bending of the materials but atthe same time make it possible to bend the material to a substantialdegree without increasing the yield point of the material, i.e. withoutcausing permanent deformation.

These and other objectives can be achieved therein that the height ofthe arcs projected on the X-Y-plane, arc height being defined as theextension of the arcs in the Y-direction within said zone, is at leastas large as or larger then the wave length of said waves alternating inthe Z-direction.

The corrugation or the embossing within the region of the conceived,strip shaped zone of the material thus consists of ridges and valleysalternatingly, said ridges and valleys extending in the shape of arcsover the breadth of the zone. These arcs preferably consist of parabolasbut they can also have other shapes, e.g. be circular arcs, hyperbolas,or other preferably symmetrical curves.

Disregarding the method of defining the corrugation pattern, thedistance in the longitudinal direction of the strip shaped zone, foreach of said ridges, between on one hand the points of intersectionbetween the crest line curve and the zone edges, and on the other handthe point of intersection between the crest line curve and a plane inthe longitudinal direction of the zone, perpendicular to the zero planeor basic plane of the material and the tip point of the intersectingarc, is at least as large as or larger than the distance between saidtip point and the tip point on an adjacent ridge.

The material can exhibit a single zone of the above mentioned type orseveral such zones, which are arranged parallel to each other, and eachof which exhibits the said arc shaped corrugation pattern, and thesearcs may be arranged in the same or in opposite directions, as isindicated in the appending claims. Preferably the ridges and valleysflat out in those edges of the material which are parallel with thelongitudinal direction of the zone or the zones.

Preferably the above described corrugation is superimposed on a basicshape of the material, in which the basic shape is arcuated in a planeperpendicular to the longitudinal direction of said zone or zones. Moreparticularly the basic shape of the material in said plane preferablyforms an arc within each corrugated zone, i.e. the material is arcuatedwithin the zone, and the described corrugation has been superimposed onthis arcuated shape, so that the corrugation itself has been afforded anarcuated shape perpendicular to the longitudinal direction. If thematerial has more than one corrugated zone, which it normally hasaccording to the invention, the material can be arcuated in differentdirections. If the number of zones is two, the basic shape of thematerial thus will have an S-shape in cross section.

Further features and aspects of the invention and of the corrugationpattern will be apparent from the appending claims and from thefollowing description of various embodiments.

Typically, the material of the invention consists of a thin, coldrolled, hardened and tempered steel strip. This material, which exhibitsthe embossing pattern characteristic for the invention can be used e.g.for

measure tapes,

so called strip antennas for in the first place portable radio and TVreceivers,

springs, particularly for rolling up springs for e.g. wind-up drums forflexible cables for vacuum cleaners and other electrical apparatuses,for winding up starting straps for combustion engines, for winding upsafety belts in motor cars, etc.,

spring elements in shock absorbers, power equalizers, etc., in whichcases the material may be comparatively broader.

The principals of the invention also can be used for other elasticmaterials than metallic materials, e.g. for paper, paper board andplastic, as well as for composite materials containing one or more ofsaid materials. Within this area the material of the invention may beused as packaging material. It is also conceivable to combine severallayers of the material of the invention and to unite these layers witheach other to form a sandwich material having a good bendability but atthe same time desired stiffness.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be explained more in detail in the following withreference to some conceivable embodiments and also through thedescription of performed tests. Herein reference will be made to theaccompanying drawings, in which

FIG. 1 is a perspective view of a strip of the invention with acorrugated zone extending over the entire breadth of the strip;

FIG. 2 is a longitudinal section through the strip in a symmetry planealong the line II--II, in FIG. 1;

FIG. 3 is a longitudinal section through the strip along a line III--IIIin FIG. 1;

FIG. 4 is a side view of the strip along the line IV--IV in FIG. 1,

FIG. 5 is a perspective view of a strip having the same embossingpattern as the strip in FIG. 1 but with the difference that the ridgesand the valleys in the corrugation pattern flat out in the strip edges;

FIG. 6 is perspective view of a strip having two corrugated zones,wherein the corrugation of the two zones continue into each other sothat the ridges and the valleys form S-shaped patterns;

FIG. 7 is a perspective view of a fourth embodiment of a strip of theinvention exhibiting two corrugated zones and between these zones anon-corrugated zone;

FIG. 8 shows a strip in a cross section along a line VIII--VIII in FIG.7;

FIG. 9 illustrates a fifth embodiment of the material according to theinvention which has the shape of a sheet or a plate having a pluralityof zones with continous corrugations;

FIG. 10 illustrates in a perspective view how a strip according to asixth embodiment of the material according to the invention is subjectedto bending, in which embodiment the corrugation has been superimposed ona single arcuated basic shape;

FIG. 11 is a perspective view illustrating a seventh embodiment of theinvention in a shape of a strip having two zones with the corrugationpattern of the invention which has been superimposed on a basic shapewhich is sinusoidal or slightly S-shaped in cross section;

FIG. 12 shows the sinusoidal strip in an end view XII--XII in FIG. 11;

FIG. 13 is a perspective view of a sandwich element consisting of aplurality of sheets stacked on each other, each or every second of saidsheets being corrugated according to the invention;

FIG. 14 is a chart illustrating the bending moment versus the invertedvalue of the radius of curvature of the strip caused by bending thetests of strips designed according to various embodiments of theinvention;

FIG. 15 is a tensile chart from bending tests performed on a strip withthe corrugation pattern of the invention but with a flat basic shape andeven, straight edges, where the corrugation pattern flat out; and

FIG. 16 shows a corresponding tensile chart from testing a strip havingthe same corrugation pattern as in FIG. 15 but superimposed on aarcuated basic shape.

The thicknesses have been strongly exaggerated in the shown sectionalviews.

DESCRIPTION OF PREFERRED EMBODIMENTS Embodiment I

This embodiment, which is illustrated in FIGS. 1-4, concerns a stripshaped product, more particularly a comparatively narrow strip shapedproduct 1. The material preferably consists of a thin, hardened andtempered steel, but also other materials can be used, as has beenmentioned above, provided the material is elastically deformable in thechoosen dimension.

The material has a flat basic form according to embodiment I as well asaccording to the following embodiments II-V. The embossing pattern issuperimposed on this flat basic form, and has according to theembodiment the shape of identically shaped ridges 2a, 2b, 2c . . . 2nwhich alternate with valleys 3a, 3b, 3c . . . 3n and are continouslyrepeated along the length of strip 1. The zero-plane of strip 1 has beendesignated 4 in FIG. 2. The zero-plane 4 according to the embodimentcorresponds to the center plane of the flat starting material and withthe X-Y-plane in a conceived three dimensional coordinate system havingthe X-direction perpendicular to the longitudinal direction of thestrip, the Y-direction coinciding with the longitudinal direction of thestrip, and the Z-direction perpendicular to the zero-plane. Further, theY-Z-plane coincides with a longitudinal plane of symmetry of strip 1.

The center line 5 of the strip forms a waved curve in a sectioncoinciding with the said plane of symmetry as in each section parallelwith this Y-Z-plane, more particularly a sine-wave curve whichsymmetrically alternates about the zero-plane 4. The amplitude A of thewave thus corresponds to the embossing depths. The strip thickness hasbeen designated T. The wave length of the sine-wave is designated L.

The lines along the ridge crests, hereinafter referred to as ridge crestcurves, are designated 6a, 6b, 6c, etc., while the bottom lines of thevalleys are designated 7a, 7b, 7c, etc. The ridge crest curves 6a, 6b,6c, etc., as well as the bottom lines 7a, 7b, 7c, etc., definecontour-lines or so called isohypsis, with a terminology borrowed fromtopography,. i.e. lines defined by points lying at equal height above orat equal depth beneath a certain zero-plane, in this case zero-plane 4.According to the embodiment the ridge crest curves 6a, 6b, 6c, etc. andthe bottom lines 7a, 7b, 7c, etc. as well as all contour-lines on theridges or on the slopes of the valleys between the ridges and the bottomlines form arcs when projected on the zero-plane, which arcs aresymmetrical about the Y-Z-plane (the plane of symmetry). Moreparticularly the said arcs have the shape of parabolas which extend overthe entire breadth of the strip, having the nose of the parabola in thesymmetry plane.

The strip edges have been designated 8. The points of intersectionbetween the ridge crest curves and the strip edges are designated 9, andthe nose points of the ridge crest curves are designated 10. Thedistance in the Y-direction between one of the first said points 9 andthe nose point 10 on the same ridge crest curve, e.g. the ridge crestcurve 6c, is referred to as the phase difference F of the wave patternin this context. The termwave pattern in this context is used for thepattern which is generated by the previously mentioned waves in theY-Z-plane and planes parallel with the Y-Z-plane. According toembodiment I the phase difference F has at least or approximately thesame length as the wave length L, i.e. corresponding to about 2π rad or360°.

The tension forces in the material can be distributed very evenly in thematerial due to the described embossing pattern such that the yieldpoint of the material is not exceeded, even if the strip is subjected toextreme bending in the Z-direction. This is due to the fact that theredoes not exist any tangent in any point of the embossing pattern on thesame side of the plane of symmetry having the same inclination ordirection as any other tangent. Because of this, if the strip issubjected to bending in the Z-direction, there is caused a shearrelative to all adjacent volume elements of the strip, also in the X-and Y-directions. This implies that the shearing resistance in alldirections of the entire material volume is utilized, i.e. in the X- aswell as in the Y- and- Z-directions, although the bending is performedonly in one of the directions; the Z-direction. This implies there isachieved a more even distribution of the tension forces, which arespread out over a larger volume region, and also with a larger totaltension or accumulated power as compared with a conventional striphaving a conventional C-profile or an S-profile, at the same time as acorresponding bendability is maintained. This means that it is possibleto achieve a considerably larger stiffness in combination with anequally good bendability of the strip as for non-embossed flat or C- orS-profiled strips, although the embossing depths A is rather small.Normally the following expression applies: 0.5 T<A<2 T, where T=thethickness of the strip.

Embodiment II

In embodiment I the wave pattern extended with equal amplitude all theway out to the strip edges 8. This has the drawback that tensionconcentrations may occur in the edge zones when the strip is subjectedto a bending moment which may initiate buckling of the strip. Theembodiment illustrated in FIG. 5 aims at eliminating this drawback.Therefore ridges 2a', 2b', etc and valleys 3a', 3b', etc flat out thetwo edge zones 13, FIG. 5, therein that the amplitude A, whichcorresponds to the embossing depth, successively approaches and reacheszero in the edge zones 13. The amplitude of the wave pattern in thestrip edges 8' thus is zero according to embodiment II. The edge zones13 has a breadth corresponding to the distance between section III--IIIand corresponding strip edge 8'. The rest of strip 21, FIG. 5, isembossed in a mode which is identical to corresponding parts of strip 1according to embodiment I and may, as a compensation for the diminishingembossing depth in the edge zones be afforded an increase of the phasedifference in comparison to the wave length.

Embodiment III

This embodiment is suitable for somewhat broader strips than in theembodiments I and II. A strip according to embodiment III is designated31 in FIG. 6. The strip edges 8' are straight, as in accordance withembodiment II. The ridges 32a, 32b, 32c, etc. and valleys 33a, 33b, etc.thus are flattening out therein that the amplitude of the embossingpattern .successively is reduced to zero. Ridges 32a, 32b, 32c, etc.,and valleys 33a, 33b, etc., however, in this case form S-shaped curveswhen projected on the X-Y-plane, the ridge crest curves 36a, 36b, etc.,and the bottom lines 37a, 37b, etc. forming two parabola sections. Theembossing pattern on one side of the longitudinal centre line of strip31 may be said to consist of an outer half having an embossing patterncorresponding to that of embodiment II and an inner half having anembossing pattern according to that of embodiment I. On the other sideof the centre line of strip 31, the pattern is turned to the otherdirection, i.e. such that the parabola noses point to the oppositedirection in relation to the noses on the other side of the strip,wherein there is obtained the S-shaped wave pattern of ridges andvalleys shown in FIG. 6.

Embodiment IV

FIG. 7 illustrates a strip 41 according to embodiment IV as seen in aperspective view. The embossing pattern of strip 41 corresponds to twostrips 21 of embodiment II, FIG. 5, lying adjacent to each other andbetween these two conceived strips a flat centre zone 40. Any moredetailed description of the embossing pattern should not be required butinstead is referred to the description of embodiments I and II in theforegoing and to the cross section IX--IX shown in FIG. 8. Strip 41 canbe used for springs, measure tapes etc. When using the strip for ameasure tape the flat center zone 40 can be used for a scale.

Embodiment V

In FIG. 9 a broader piece of paperboard, sheet or plate according toembodiment V is designated 51. It exhibits a greater number of embossingzones 50a, 50b, 50a, 50b, etc., arranged side by side. These zones areidentically alike and designed as in embodiment I but every second oneis turned the other way round such that the ridges 52a, 52b, etc. andthe valleys 53a, 53b, etc. continously and meanderlike extend over thewhole breadth of sheet 51 from edge to edge 8.

The sheet, foil, plate or corresponding 51 thus embossed can be used asa spring member when it is made of metal, e.g. of hardened steel. It canalso be used as a construction material, e.g. if the material consistsof a thin sheet of for example steel, copper, or aluminum. It is alsoconceivable that the sheet consists of paper, board, or plastic orcomposite materials which contains one or several of the said materials.As distinguished from corrugated board or other corrugated sandwichmaterials this embodiment may provide a material which is stiff butwhich can be bent in all directions and which therefore has excellentproperties for the use as a packaging material.

FIG. 13 shows a sandwich element 81 made of a plurality of sheets 51,wherein between each such sheet 51 there is provided a flat sheet 82.

The different layers in the sandwich element 81 are secured to eachother e.g. through welding, gluing or by means of any adhesive material.

Embodiment VI

In order to increase the bending resistance of the material, theparabolas or the circular arcs also may be afforded a curvature in theX-Z-plane by affording the material an arcuated shape in the said plane.FIG. 10 (and also FIG. 16) illustrates in a perspective view a portionof an arcuated strip 61. The embossing pattern is superimposed on thearcuated shape so that the parabolas or circular arcs are bent also inthe X-Y-plane on or in the arcuated shape, which is also shown in FIG.16.

Embodiment VII

This embodiment is illustrated in FIGS. 11 and 12. It has the shape of astrip 71 exhibiting two zones 70a and 70b, each of which is providedwith an embossing pattern according to embodiment II, which is appliedon a sinusoidal (S-shaped in cross-section) basic shape of the strip,which is illustrated in FIG. 12. Each zone 70a and 70b, respectively,can be regarded as arcuated as strip 61, but the arcs are turned inopposition directions, so that the strip receives a convex-concave orslight S-shape in cross section, in FIG. 12. Due to this convex-concaveor S-shaped cross section, the strip 71 is afforded the same bendingresistance in the negative and in the positive Z-direction.

The strip 71 is designed in the first place for measure tapes. A centrezone 70c therefore is provided with a tooth formed embossing patternsuitable for magneto resistive detection, although also other detectionor sensing methods can be used with this pattern, i.e. mechanical,optical or purely electrical.

Due to the embossing pattern of the invention which has beensuperimposed on the S-shaped basic shape of the strip, a measure tapemade of the strip 71 has a stiffness which is several times larger thana conventional steel measure tape having the same material features,including the same thickness. It is also a characteristic feature of thestrip of the invention, and this particularly concerns the abovedescribed embodiments, that it is not particularly disposed to bucklingor collapsing when subjected to overloading as is typical forconventional steel measure tapes, but is as far as these features areconcerned more like a conventional folding rule and is stiff in asymmetrical mode because of the sinusoidal (S-shaped) basic shape, atthe same time as the strip can be reeled up in a strip housing.

The practical importance of these features is that the strip 71 is notflabby as conventional measure tapes but instead can be handled in amode similar to that of a folding rule because of its stiffness. Thesinusoidal basic shape (the S-shape, FIG. 12) also allows the strip torest stable against a support so that lines can be drawn and markings bemade along the scale using the strip 71 as a ruler, and wherein themillimetre markings on the edge zones 70d can be read close to theobject in contrast to the conventionally arcuated (C-shaped) measuretapes which have a pronounced tendency to rock. Thanks to thesymmetrical stiffness of the sinusoidal and micro-corrugated strip 71 itis also possible to hold the strip vertically upwards, e.g. inconnection with measuring against a ceiling or the like, without thestrip falling down even if the height to the ceiling is considerable,which is a problem when using conventional steel measure tapes.

A strip having the embossing pattern of the invention superimposed on anarcuated or sinusoidal basic shape, as in accordance with strip 71, isalso very advantagous to use as an antenna for portable radio or TVreceivers. In this case of course no scale is necessary as has beendescribed above. The material advantageously also can be used forsprings which desirably shall have the same stiffness in bothdirections.

Experiments

Steel strips having a breadth of 6.5 mm and a thickness T=0.12 mm wereused as test samples. In one case there was used a strip 21 according toembodiment II, FIG. 5, i.e. a strip having a flat basic shape and inthree other tests there was used a arcuated strip according toembodiment VI, FIG. 10. The wave length L of the corrugation, FIG. 2,the embossing depths or amplitude A, FIG. 2, and the phase difference F,see above under heading embodiment I, were varied. The arcuated strips(C-shape) had an arcuation radius of 10 mm.

For the four tested strips, the following parameters applied:

                                      TABLE 1    __________________________________________________________________________            Thickness                  Wave length                         Amplitude A                                   Phase difference                                            Radius of       Breadth            T     L      (embossing depths)                                   F        arcuation    Strip       mm   mm    mm     mm        rad      mm    __________________________________________________________________________    21 6.5  0.12  4.5    0.094     2π    flat    61A       6.5  0.12  6.0    0.11      13/6π 10    61B       6.5  0.12  4.5    0.10      13/6π 10    61C       6.5  0.12  4.5    0.10      13/6π 10    __________________________________________________________________________

The four strips were subjected to varying bending moments resulting inmore or less pronounced bending. The ratio between bending (invertedvalue) and the bending moment is seen in the chart in FIG. 14. In thischart, there is also included a corresponding chart for a completelyflat, non-embossed strip having the same breadth, thickness and qualityas the strips listed in the table.

The highest bending moment was measured for strips 61A and 61B which aresubjected to bending against the concave side of the C-shape, but if thegraphs are extrapolated, strip 61C, which strip is subjected to bendingagainst the convex side of the strip, will intersect the other graphs. Alinear ratio and as high bending moment as possible are desired. Thebasic shape for the tested strips and the load direction have also beenindicated by symbols in the chart. Strip 61B and 61A were bent towardsthe convex side of the strip, while strip 61C was bent towards theconcave direction. This indicates that there is a certain asymmetrydepending on convex or concave bending direction. This asymmetry,however, is strikingly small.

A number of conclusions can be drawn from the chart. Thus there isobtained a higher stiffness, i.e. a larger bending moment, if theembossing depth is increased; strip 61A as compared with 61B. Strip 61Chas a linear characteristic within a large region of the graph whichimplies that the strip can be bent to a smaller radius without permanentdeformation. In this respect, however, strip 21 has the bestcharacteristic, i.e. is almost linear. On the other, the bendingresistance is substantially smaller than for strips 61A-61C.

Most striking, however, is that the combination of the arcuated(convex/concave) basic shape and the embossing pattern superimposed onthis basic, shape affords an extraordinarily high increase of thematerial stiffness to the strip. If for example the completely flat,non-corrugated strip has a stiffness (bending moment) having an index 1,the embossed strip 21 of the invention having a flat basic shape willget a stiffness index 4, while the arcuated and embossed strips 61A-61Cobtain a stiffness index in the order of 12. This shows that a clearsynergism is obtained by combining the corrugation and the arcuation ofthe corrugated strip zone.

In the described embodiments the embossing has been made symmetricallyabout the zero-plane 4, FIG. 2. It is, however, possible to make theembossing asymmetric relative to the zero-plane 4, wherein it ispossible to obtain the effect that the strip will get a greaterresistance against bending in one Z-direction than in the opposite one,which may be a worthwhile feature if the strip shall be used e.g. as aspring. It is also possible to make use of this asymmetry in order tocompensate for the slight asymmetry caused by the C-shape, as shown bythe difference between 61B and 61C, in order to provide a symmetricstiffness of the strip or the sheet without using a sinusoidal orS-shape.

The graphs for strips 61A-61C shown in FIG. 14 successively flatten out,which is not shown in the chart, such that the graphs asymptoticallyapproach a given, almost constant bending moment. This implies thatthere is obtained a constant bending resistance within a large regionundependent on the radius of curvature of the strip caused by bending(note inverted value of the radius of curvature in FIG. 14). This is avery interesting feature for flat springs, since this makes it possibleto provide springs with very well defined spring parametres, so calledconstant springs.

The several times increased stiffness combined with a maintainedbendability has a considerable economical value, i.a. because of anincreased spring power per volume of spring material and also throughthe versatility of the various embodiments which are useful for variousapplications.

Due to the fact that the invention comprises a number of variousparameters which can be varied, such as the embossing depth, phasedifference, wave length, the radius of the arcuation (the basic shape),and possible asymmetry of the embossing relative to the zero-plane,there are afforded great opportunities to design materials according tothe invention having various desired properties, i.e. springs havingspecific spring parameters or materials which have an extreme stiffnessbut which nevertheless can be bent without causing permanentdeformation. The latter features are also illustrated by FIG. 15 andFIG. 16 which show the tension distributions in strips according toembodiment II and embodiment VI, respectively, when the strips aresubjected to bending moments. In the diagrams in FIG. 15 and FIG. 16,regions having equal tension levels are indicated. These diagrams showthat the tensions are distributed in an advantagous mode over thesurface of the strip which implies that the strips have a significantbuckling resistance.

I claim:
 1. A metal strip having increased longitudinal and transversestiffness, high bendability without permanent deformation, and springcharacteristics, comprising:at least one corrugated zone along a lengthof the strip and corrugations of the corrugated zones having ridges withvalleys therebetween with an isohypsis of said ridges and valleysforming arcs when projected on an X-Y plane of a three dimensional X-,Y-, Z-direction system in which the X-direction coincides with a widthof the corrugation zone, the Y-direction coincides with a length of thecorrugation zone and the Z-direction is perpendicular to the X-Y planeand longitudinal sections through the corrugated zone form waves in theY-Z plane, propagating in the Y-direction and alternating in theZ-direction, said waves having a wave lengths and being in acontinuously curved configuration; and wherein (a) a depths of thecorrugations were 0.5T<A<2T, where T is a thickness of the strip, A is acorrugation depth defined as the amplitude of the wave pattern from acenter line of the strip in a symmetry plane of the corrugation zonecoinciding with a tip of the arc of the ridges projected on the X-Yplane; and (b) the height of the arcs was at least as large as the wavelength of said waves alternating in the Z-direction.
 2. A stripaccording to claim 1, wherein the arcs are parabolas.
 3. A stripaccording to claim 1, wherein the strip has at least two parallelcorrugation zones, each of which exhibits said corrugation pattern.
 4. Astrip according to claim 3, wherein the arcs point in the same directionin each corrugated zone.
 5. A strip according to claim 4, wherein thearcs in one zone point in a different direction than the arcs in asecond zone when the number of corrugated zones is two and pointalternatingly in different directions when the number of corrugatedzones is more than two.
 6. A strip according to claim 3, wherein thereis a zone between the corrugated zones which is not corrugated or doesnot have arcs.
 7. A strip according to claim 1, wherein the shape of thestrip is in the form of an arc within each corrugated zone.
 8. A stripaccording to claim 7, wherein the strip is arcuated in oppositedirections within areas of adjacent corrugated zones such that the shapeof the strip in the said X-Y plane is essentially S-shape when the striphas two corrugated zones, and is essentially a repeated sinusoidal shapewhen the strip has more than two corrugated zones.
 9. A strip accordingto claim 1, wherein the strip is cold rolled, hardened and temperedsteel having a thickness (T) of 0.01-1.0 mm.
 10. A strip according toclaim 1, wherein the strip has two corrugation zones and between thesetwo zones has a zone with a corrugation pattern suitable formagneto-resistive reading.
 11. A strip according to claim 1, whereincrests of the ridges and bottoms of the valleys are asymmetricallydisplaced in relation to a mean level of the strip.
 12. The stripaccording to claim 1, wherein the strip has edges outside of thecorrugation zone.
 13. The strip according to claim 1, wherein the striphas a curved shape in the Z-direction, the corrugation beingsuperimposed on said curved shape.